py: Tidy up exception matching; allow matching of tuple of exceptions.

Addresses issue #864.

py/obj.h

@@ -458,7 +458,7 @@ mp_int_t mp_obj_int_get_checked(mp_const_obj_t self_in);
 #define mp_obj_is_native_exception_instance(o) (mp_obj_get_type(o)->make_new == mp_obj_exception_make_new)
 bool mp_obj_is_exception_type(mp_obj_t self_in);
 bool mp_obj_is_exception_instance(mp_obj_t self_in);
-bool mp_obj_exception_match(mp_obj_t exc, const mp_obj_type_t *exc_type);
+bool mp_obj_exception_match(mp_obj_t exc, mp_const_obj_t exc_type);
 void mp_obj_exception_clear_traceback(mp_obj_t self_in);
 void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, mp_uint_t line, qstr block);
 void mp_obj_exception_get_traceback(mp_obj_t self_in, mp_uint_t *n, mp_uint_t **values);

py/objexcept.c

@@ -403,11 +403,15 @@ bool mp_obj_is_exception_instance(mp_obj_t self_in) {
     return mp_obj_is_exception_type(mp_obj_get_type(self_in));
 }
 
-// return true if exception (type or instance) is a subclass of given
-// exception type.
-bool mp_obj_exception_match(mp_obj_t exc, const mp_obj_type_t *exc_type) {
-    // TODO: move implementation from RT_BINARY_OP_EXCEPTION_MATCH here.
-    return mp_binary_op(MP_BINARY_OP_EXCEPTION_MATCH, exc, (mp_obj_t)exc_type) == mp_const_true;
+// Return true if exception (type or instance) is a subclass of given
+// exception type.  Assumes exc_type is a subclass of BaseException, as
+// defined by mp_obj_is_exception_type(exc_type).
+bool mp_obj_exception_match(mp_obj_t exc, mp_const_obj_t exc_type) {
+    // if exc is an instance of an exception, then extract and use its type
+    if (mp_obj_is_exception_instance(exc)) {
+        exc = mp_obj_get_type(exc);
+    }
+    return mp_obj_is_subclass_fast(exc, exc_type);
 }
 
 // traceback handling functions

py/runtime.c

@@ -263,18 +263,25 @@ mp_obj_t mp_binary_op(mp_uint_t op, mp_obj_t lhs, mp_obj_t rhs) {
     if (op == MP_BINARY_OP_EXCEPTION_MATCH) {
         // rhs must be issubclass(rhs, BaseException)
         if (mp_obj_is_exception_type(rhs)) {
-            // if lhs is an instance of an exception, then extract and use its type
-            if (mp_obj_is_exception_instance(lhs)) {
-                lhs = mp_obj_get_type(lhs);
-            }
-            if (mp_obj_is_subclass_fast(lhs, rhs)) {
+            if (mp_obj_exception_match(lhs, rhs)) {
                 return mp_const_true;
             } else {
                 return mp_const_false;
             }
+        } else if (MP_OBJ_IS_TYPE(rhs, &mp_type_tuple)) {
+            mp_obj_tuple_t *tuple = rhs;
+            for (mp_uint_t i = 0; i < tuple->len; i++) {
+                rhs = tuple->items[i];
+                if (!mp_obj_is_exception_type(rhs)) {
+                    goto unsupported_op;
+                }
+                if (mp_obj_exception_match(lhs, rhs)) {
+                    return mp_const_true;
+                }
+            }
+            return mp_const_false;
         }
-        assert(0);
-        return mp_const_false;
+        goto unsupported_op;
     }
 
     if (MP_OBJ_IS_SMALL_INT(lhs)) {